CMMG has announced that—after durability testing—its MkG GUARD pistol caliber carbine in .45 ACP, which is fed from factory Glock magazines, is now safely rated for 450 SMC. More on that round below, via the presser:

For those unfamiliar with 450 SMC, Triton first conceived the cartridge in 2001. The design was ultimately taken over and completed by DoubleTap ammunition years later. In essence, it is a magnum version of .45 ACP that offers ballistics that are comparable to 10mm. It is a true “stopper” that delivers energy capable of taking down big game.

While the 450 SMC uses a case with the same outer dimensions as .45 ACP, there are a few significant differences that allow DoubleTap to load 450 SMC with five to six thousand pounds per square inch of pressure more than a standard .45ACP. First, the 450 SMC uses a small magnum rifle primer instead of the large pistol primer. This modification allows the hardened case to be thicker at the base. Second, the brass is manufactured from the ground up to handle up to 30,000 pounds of pressure. The result is a dual-purpose cartridge that is exceptional for both hunting and personal defense.

The company notes that while 450 SMC can be run in any .45 ACP rifle rated for +P ammo, the rearward force created by the load would cause issues in a straight blowback AR15. The MkG GUARD is able to mitigate those issues due to its Radial Delayed Blowback system.

The Radial Delayed Blowback system uses up some of the recoil impulse of the spent round to unlock the rotating bolt from the barrel extension. This mitigates the leftover rearward force that then drives the carrier back to cycle the action. By eliminating some of this rearward force during the unlocking sequence, the GUARD requires less weight in the bolt carrier group and buffer to safely cycle. This reduction in reciprocating mass results in less felt recoil for the end user.

See below to check out how the 450 SMC compares to the 10mm out of a 16-inch barrel, according to data supplied to CMMG by DoubleTap. In addition see the specs for CMMG’s MkG GUARD platform. For more, visit cmmginc.com.